/Engine/Source/Developer/ToolWidgets/Public/Filters/SBasicFilterBar.h
Makes the button that summons the Add Filter dropdown on click
static [TSharedRef](API\Runtime\Core\Templates\TSharedRef)< [SWidget](API\Runtime\SlateCore\Widgets\SWidget) > MakeAddFilterButton ( [TSharedRef](API\Runtime\Core\Templates\TSharedRef)< [SBasicFilterBar](API\Developer\ToolWidgets\Filters\SBasicFilterBar)< FilterType >> InFilterBar )